It's easy to get answers about health and nutrition! Just send your question by email to firstname.lastname@example.org and Dr. Harlan will respond to selected questions of general interest. Answers will be posted in the Ask Dr. Gourmet newsletter (sign up now!) and archived in the Ask Dr. Gourmet section of the website.
My question is about spinach and specifically, what are the attributes in spinach that makes one's tongue and teeth feel "funny" after eating? I love spinach, but I don't like this after effect and recently I thought, "Hmm, I wonder if Dr. Gourmet knows what causes this?"
I have asked a few experts on this and performed a literature search. Neither of these were very revealing for a definitive answer but there are three possible explanations that came up more than once in my questioning:
1. Iron. Spinach is high in iron and you may be tasting that.
2. Tanins. Spinach, like red wine, is high in tannins. These molecules are the ones responsible for the astringent "puckered" mouth effect.
3. Oxalic acid. (This is the most popular theory.) Similar to tannins, these molecules also have an astringent effect and many describe a "chalky" effect after consuming foods high in oxalic acid.
Thanks for writing,
Timothy S. Harlan, M.D.